Known in the art are methods for a thermal decontamination of waste waters contemplating evaporation of waste waters in evaporators of different types, combustion of wastes in chamber-, shaft-, cyclone-type and other combustion means.
These prior art methods have a disadvantage residing in impossibility of utilization of thermal decomposition in the case of heavily contaminated wastes tending to foam and having a high content of slimes, suspensions and mechanical impurities. However, there is known in the art a methhod for a partial thermal purification of waste waters from surfactants by combustion of a float-condensate (cf. Klein S. A., McGayhey P. H.--Journal Water Pollut. Control Federat. 1963, 35, No. 1, 110).
Foam is formed by bubbling air by means of a perforated plate through the layer of waste waters. Foam is blown off by means of an air jet from the layer top and delivered to the combustion compartment, wherein it is destroyed and the resulting drops of a float-condensate are incinerated along with the fuel.
This prior art method also has a disadvantage which resides in that it enables elimination of only surfactants passing into the float-condensate and a minor portion of mechanical impurities, whereas the main portion of the contaminants remains in the waste water, since upon destruction of the surfactants their floatation properties disappear.
It is an object of the present invention to provide a highly-efficient method for a thermal decontamination of waste waters.
This and other objects of the present invention are accomplished by the method for thermal decomposition of waste waters in accordance with the present invention, wherein a combustible gas is passed into the waste waters for the formation of a combustible foam and surfactants are added thereto to convert the entire volume of the waste waters to the combustible foam.
This method ensures formation of foam containing a combustible gas in its bubbles. An extensively developed surface of contact between the high-temperature products of combustion of the combustible gas and foam bubbles defines a high intensity of heat- and mass-transfer processes. The foam is rapidly evaporated, the combustible gas is liberated therefrom and is combusted along with the foam particles.
It is desirable that introduction of the combustible gas into the waste waters be effected by bubbling under a gauge pressure to ensure a moving stream of the combustible foam.